The metal is silver-white, translucent, and smooth as glass but warmer and heavier. It is said to glow slightly. It is the hardest substance the Nephilim know of, and can only be manipulated, shaped and carved, by Iron Sisters, who use seraphic Marks unknown to non-Sisters, and forges in the Adamant Citadel that take fire from the heart of a volcano.
According to Sebastian Morgenstern, the Mortal Instruments are also made of adamas. He later used it to create a demonic version of the Mortal Cup, called the Infernal Cup, with the help of Sister Magdalena.
In Ancient Greek, "adamas" (ἀδάμας) is of Semitic origin—it means unconquerable, invincible, untamed, proper, unalterable, and unbreakable. Adamas is also related to the Greek word variant "adamant" and the Latin word "diamant", which translates or refers to the "the hardest metal, diamond".
- Though the touch of adamas is deadly to common demons, Greater Demons are able to resist it—although it is extremely painful to do so. In the case of Fallen Angels, this pain makes them feel a spark of the divinity they once had.